Interannual changes of fish community structure and keystone species in the waters off southern Shandong Peninsula from 2016 to 2018

In the context of large-scale enhancement and releasing, in order to study the stability of fishery ecosystem and the change of community structures in the waters off southern Shandong Peninsula, based on the waters off Southern Shandong Peninsula fisheries resources investigation and fishery species feeding literature data from 2016 to 2018, through the food web topology structure and social network analysis, we studied the southern Shandong Peninsula sea fishery resources structure and interannual variability of keystone species. The results showed that, a total of 20-22 fish species were involved in the food web of the waters off southern Shandong Peninsula, which covered 59-65 prey-predator relationships, and these are no obvious interannual changes. Based on the dominance analysis, the dominance of Larimichthys polyactis, Trichiurus lepturus, Scomberomorus niphonius increased significantly in 2018 after the adjustment of summer fishing moratorium.The topological structure density of these food webs ranged from 0.3048 to 0.3684, and interspecies connectivity was 0.1451 to 0.1634. From 2016 to 2018, the keystone species in the fish community in the waters off Southern Shandong Peninsula were Engraulis japonicus and Lophius litulon. E. japonicus as the key prey and L. litulon as the key predator, they were both the dominant species 2016-2018, however, the dominance of E. japonicus decreased with each passing year, and Liparis tanakae has been the dominance species since 2017. The results showed that the food web structure in the waters off southern Shandong Peninsula was relatively stable, with little inter-year differences, and the keystone species did not change, but the energy flow and information transfer in the community gradually evolved from high trophic species to low trophic species.